Re: Building up push ups?
EDT is always an interesting way to go. You could do around 100 push ups per workout, and do, say 15 on the minute, for around 7 min. Then 17 for 6 min., etc..., keeping the number of reps nearly the same, while reducing the amount of rest time you give yourself. It's essentially like many of the CF WODs, only paced.
If this is your goal, doing a lot of push ups will almost universally work, whether you do ladders, GTG, EDT. Pavel Tsatsouline has a whole bunch of Push Up programs detailed, where you do push ups throughout the day (every hour, or so). There is also a 100 push up program on the web. Making it part of your daily routine seems to be a wise thing to do in such cases.